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Diabetes Mellitus: Commonly Diagnosed, Commonly Miscoded

Apr 22, 2024 | News

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Diabetes mellitus affects more than 38 million Americans and is one of the most frequently miscoded diagnoses for risk adjustment. Miscoding can be a product of under-documentation, of providers not understanding coding rules that may impact documentation, or simply miscoding. Let’s look at some of the simple changes providers can make that will impact the accuracy of documentation and coding.

One of the most common errors is simply documenting “diabetes,” without addressing any complications the diabetes has caused. Physicians mistakenly assume that because they are not managing the patient’s retinopathy or nephropathy, they should not document these conditions. But keep in mind that a patient with diabetic complications has a severity of illness that a patient with uncomplicated diabetes does not experience: the disease has advanced to unreversible organ damage. This affects medical decision-making, which can affect the level of coding.

Never document “diabetes with unspecified complication”.  Providers need to know what the complication is before they can determine if it is diabetes related. It is very rare for diabetes to cause hypertension, hyperlipidemia, or obesity. In fact, these three conditions are components of metabolic syndrome X, which is a precursor to pre-diabetes and diabetes. Those three conditions cause diabetes, and not the other way around, except in rare circumstances.

More than 90 percent of Americans with diabetes have Type 2, and this is the default for ICD-10-CM. Type 1 typically begins before patients reach their mid-20s, but those patients will grow older. The differentiation is important because Type 1 diabetics typically have a more severe form of the disease. For patients with secondary diabetes, note the cause. Any type of diabetes that is not Type 2 must be documented in every encounter, as coders/auditors cannot look at older dates of service as a reference for the current encounter.

Be sure to include the patient’s latest blood glucose or A1C in the history of present illness, as diabetes affects care, even for the most minor of chief complaints. Note what meaning the rest results have, as coders cannot interpret test results. Also note in every encounter what type of treatment the patient is receiving: diet, exercise, oral medications, or insulin.

When coding diabetes, be consistent with assigning the type of diabetes:

  • E08 Diabetes with underlying condition (cystic fibrosis, cancer, pancreatitis)
  • E09 Diabetes due to drugs or chemicals (use a T code to identify the drug or toxin)
  • E10 Autoimmune diabetes rendering the patient insulin dependent, usually beginning in childhood
  • E11 Diabetes associated with aging or obesity, usually; the most common type
  • E13 Diabetes due to a mix of autoimmune and other factors (Type 1.5) or pancreatectomy

For complicated patients, if the diabetes code does not capture the complication, report a second code to report it (for example, E11.43 Type 2 diabetes mellitus with autonomic (poly)neuropathy with K31.84 Gastroparesis).

Document any pertinent hyper- or hypoglycemia, but do not report hyperglycemia in patients undergoing a glucose tolerance test to determine if they have diabetes. Report only the new onset diabetes.

Patients who have undergone bariatric surgery may no longer have active diabetes, but if they developed diabetic complications, those remain. Report these complications of diabetes using the appropriate diabetes code (for example, E11.22 Type 2 diabetes mellitus with chronic kidney disease along with a code for the CKD stage).

What simple changes have you implemented in your documentation and coding processes?  

Written by Sheri Poe Bernard, CRC, CPC, CDEO, CCS-P, Director, Risk Adjustment Assessment and Compliance.  Granite GRC can help navigate your toughest risk adjustment challenges.  Contact us at, or call (717) 556-1090.